A plasma propulsion engine is a type of electric propulsion that generates thrust from a quasi-neutral plasma. This is in contrast with ion thruster engines, which generate thrust through extracting an ion current from the plasma source, which is then accelerated to high velocities using grids/anodes. These exist in many forms (see electric propulsion). However, in the scientific literature, the term "plasma thruster" sometimes encompasses thrusters usually designated as "ion engines".

Riding the light.